Electric incandescent lamp or discharge tube



March 29, 1949. H. GOOSKENS 2,465,797

ELECTRIC INCANDESCENT LAMP OR DISGHARGE TUBE Filed May 8, 1946 FIG 5.

FIG. 2

FIG. '8

INVENTOR HENRICLJS GOOSKENS, BY Pd/MW HIS ATTORNEY Patented Mar. 29, 1949 ELECTRIC INCANDESCENT LAMP OR DISCHARGE TUBE Henricus Gooskens, Eindhoven. Netherlands, assignor to General Electric Company, Schenectady, N. Y.

Application May 8, 1946, Serial No. 668,062 In the Netherlands November 12, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires November 12, 1961 9 Claims.

My invention relates in general to electric incandescent lamps, discharge tubes and similar electric devices, and to the manufacture thereof.

In the manufacture of electric incandescent lamps and discharge tubes it is often desirable to be able to adjust exactly, during the manufacture, determined dimensions of the lamp or tube, such as the light centre length, or the total length of the tube in the case of an incandescent lamp or discharge tube having two bases or feet. In one known method this has been achieved by cementing to the neck of the lamp or tube a metal cap and to provide on the latter the base or foot proper of the lamp or tube. When being mounted, this base is adjusted on the inner cap of metal in such manner that the lamp or tube concerned acquires the desired dimension. Subsequently the base is secured to the inner cap, for example by soldering. This method has the drawback that the inner cap has to perform a function only during the manufacture of the lamp or tube but does not play any part during the operation proper of the lamp or tube, for if it were not necessary to effectuate the adjustment of the said measure in the lamp or tube, it would be possible to mount the base of the lamp or tube directly on the neck of the bulb. The use of an inner cap of metal consequently implies loss of material.

The invention has for its object to provide means which eliminate this drawback. In this case the starting-point is formed by an electric incandescent lamp or discharge tube known in itself wherein one base or both bases of the lamp or tube are mounted on a tubular projection present on the lamp or tube envelope. The lamp or tube according to the invention is characterized in that the base of the lamp or tube bears against the terminal face or outer rim end of the tubular projection by means of a contact or seating surface.

According to the invention, the use of such a tubular projection affords the possibility of cutting off this projection, subsequent to the adjustment to the desired measure, at the required length, a possibility which does not exist with incandescent lamps or discharge tubes of the usual construction, for in the latter the terminal face or end of the bulb is formed by the sealed joint between the bulb and the stem. Owing to the fact that, in accordance with the invention, the base of the lamp or tube is provided with a seating surface which bears against the terminal face or rim end of the projection, the base assumes, with respect to the bulb vessel, a position which can be exactly determined beforehand, which is not the case with the usual forms of construction of lamps and tubes, for in the latter the base is secured as a rule, with the aid of cement, to the shoulder of the bulb, which shoulder itself is inexact as regards dimensions; With the lamp or tube according to the invention it is possible, on the contrary, to secure the base exclusively to the sides of the tubular projection and to cause the contact or seating surface, which may be formed, for example, by the bottom of the base or by a rim either interrupted or uninterrupted in the interior of the base, to bear directly against the terminal face or rim of the projection. If desired. a thin layer of lacquer having, for example, a thickness of the order of magnitude of 0.5 mm. or less may be provided between the contact surface of the base and the terminal face of the bulb vessel. Owing to its very slight absolute thickness such a layer of lacquer has substantially no influence on the exactness of the adjustment of the base on the envelope.

The connection between the envelope or bulb vessel and th tubular projection may be brought about in different ways. Thus, for example, it is possible to seal a tubular projection to the terminal face or end of the bulb vessel, already provided with a stem of a lamp or tube, to cut off at the desired length the outer end of this projection and to provide thereon a base in the manner previously described. According to one advantageous form of construction of the lamp or tube according to the invention, it is advisable, for reasons of manufacture, to make the tubular projection and the adjacentstem tube in one piece which is provided, between the said projection and the pinch, with a laterally projecting sealing flange, which flange is sealed to the bulb vessel. The diameter of this flange should preferably be so chosen as to be substantially equal to the internal diameter of the bulb neck. The piece which comprises the tubular projection and the stem tube may be manufactured in such manner that the starting-point is formed by two pieces of glass tubing each having at one of the ends a flange, said flanges being sealed together, thus forming the sealing flange for the bulb.

According to one advantageous embodiment of the invention, however, the stem is preferably made by upsetting a piece of glass tubing at a point intermediate its ends to thereby provide a double-walled sealing flange whereupon together with one or more supply wires and, as the case may be, an exhaust tube, the glass tube is locally formed into a pinch. This form of construction has the advantage that with the aid of the usual means it is possible to manufacture a stem wherein the distance between the point at which the flange is sealed to the bulb and that end-of the pinch which-is remote from the said sealing flange is 3 cms. at the most, for in the manufacture of the pinch the stem tube may be held fast in an eflicient manner, with the aid of the tubular projection, in a gripper or similar instrument. It is also possible, of course, to seal more than two supply wires into the pinch; furthermore the latter may be formed in difl'erent ways. The term pinch, or press as it is sometimes called, is to be understood in this connection to include not only seals of supply wires in a stem tube which are produced by pinching with the aid of 'pincers but also, for example, those in which the supply wires are arranged in a glass tube which closely surrounds them and the seal is established by heating the material of the stem tube to a high temperature, owing to which this material softens and encloses the supply wires.

Furthermore, according to one form of construction of the lamp or tube according to the invention, the use of a stem having a laterally projecting sealing flange as described above affords the possibility of securing the base of the lamp or tube to the envelope thereof by means of hook-shaped projections or fingers which bear against the inside of the sealing flange.

Since in the lamp or tube according to the invention the tubular projection generally has a smaller external diameter than the envelope itself, the invention makes it possible to secure, to a lamp 01' tube, bases which also have themselves a considerably smaller diameter than the lamp or tube envelope. Furthermore, by utilizing the basic idea of the invention it is possible to manufacture incandescent lamps or discharge tubes whose reproducibility of determined dimensions is much greater than is the case with the usual constructions.

The invention is hereinafter explained more fully with reference to the accompanying drawing.

Fig. 1 represents a part-sectional elevation of an electric discharge tube according to the invention.

Figs. 2 to 5 inclusive show four successive stages of the manufacture of the stem and of the tubular projection present thereon out of one piece of glass tubing (and also two supply wires and an exhaust tube).

Fig. 6 shows another method of manufacturing the stem tube according to Fig. 3.

Fig. 7 represents a modified form of construction of the one end of the tube according to Fig. 1.

Figs. 8 and 9 show two different ways of mounting the base on the tubular projection.

The discharge tube according to Fig. 1 comprises an elongated envelope or vessel I to the ends of which are sealed stems 2 and 3 provided with the usual press portions or pinches 4 and 5. The pinch 4 has incorporated in it supply wires 6 and I which jointly support an electrode 8, and an exhaust tube 9. The pinch 5 has sealed therein supply wires I0 and II which act as supports for an electrode I2.

Apart from the presence of. the exhaust tube 9 in the stem 2, which exhaust tube is not present in the stem 3, these stems are of the same construction so that the description of the construction of the stem 2 is suilicient. This stem 2 is provided, in addition to the pinch 4, with a flange I3 for scaling to the envelope I, and with a tubular projection I4.

After the stem 2 has been completed in the manner which will be described hereinafter, it is sealed into the bulb I at the region of the peripheral zone A of the sealing flange I3. In

a similar manner the stem 3 is connected to the other end of the bulb. In this sealing operation it is possible either to seal the edge of the bulb to the flange I3 or to slip the bulb over the latter and then form the seal, in which latter case the remaining portion of the bulb outwardly of the seal becomes waste. After thestems have been sealed in, the tube is exhausted by means of the exhaust tube 9 and, as the case may be, filled with gas, whereupon at a point located within the tubular projection I4 this exhaust tube is sealed off, which may be effected, for example, by means of an electric heating element placed around the said exhaust tube. The discharge tube is then adjusted to a determined dimension, which dimension in the particular case under consideration is the total length of the tube.

To that end the tube is placed in a former and marks are provided on the tubular stem projections I4 in such manner that the distance a between these marks corresponds to the length of the tube without bases. After these marks have been provided the projections I4 are cut oil at these desired lengths, which is directly possible owing to the tubular form of the projections. Alternatively, it is possible to arrange two parallel grinding discs at such a distance from one another that this distance exactly corresponds to the desired length of the tube without bases. In this case the sealed-in tube may be brought directly between the grinding discs by which the projections I4 are cut off at the desired length. Finally bases I5 and I6 are mounted on the projections I4 in such manner that contact or seating surfaces of these bases bear against the terminal faces or outer rim ends of the projections. All this is shown to an enlarged scale in Fig. 8 which represents the left-hand end of the tube according to Fig. 1. Against the terminal face or outer rim and IT-I I of the projection I4 bears the bottom I8 of the base I5. If two bases I5 having a bottom thicknes 1) according to Fig. 8 are secured to a tube having the length a indicated in Fig. 1, the length of such a tube is reproducible with great accuracy since the bases can be manufactured with great precision (for example, by moulding out of artificial resin, brass and the like). These bases I5 may be solely attached to the side-wall I9 of the tubular projection I4, but also in the case where a thin layer of lacquer having, for example, a thickness of the order of magnitude of 0.5 mm. or less is provided as a means of attachment between the terminal face or rim I'I-I'I of the tubular projection I4 and the contact or seating surface of the base I5 the total length of the tube with the bases remains sufliciently exact. The contact surface of the base of the tube need not be formed, of course, by the bottom of the base but a rim, either interrupted or uninterrupted may also be utilized as such. If desired, at the region where it engages the terminal face or rim II-II, the base I5 may be provided with a contraction and in its central portion a cavity which extends further on. The ends of the supply wires 6 and I pass over the terminal face or rim I'I-I I of the projection I4 and through narrow channels iBa provided in the side-wall of the base i5. These channels open into grooves which are provided in the outer wall of the base and in which the ends of thesupply wires are arranged. Then the grooves are filled with solder |5b and this in such manner that the outside of this solder coincides with or lies flush with the outside wall of the base,.the external current supply contacts being thus iormed.- All this may also b effected, however, in any other manner.

In the case illustrated in Fig. 1 it was the total length of the tube which was adjusted by cutting to length the projections [4. It is also possible, of course, to adjust in a similar manner other values, for example, the light centrelength, indicated by c in Fig. 1, in the case where the portion shown in section in Fig. 1 represents part of an electric incandescent lamp with one base and the element 8 consequently represents a filament. Figs. 2, 3 and 4 show the manner in which, in accordance -with the invention, the stemrepresented in,Fig. 5 may be made f1 m a piece of glasstubing denoted by in Fig. 1. To that end the zone B of this piece of glass tubing is heated until it softens with the aid of burners, diagrammatically indicated byarrows 2 I, whereupon by submitting the said piece of glass tubing to a pressure exerted in the direction of arrows C, the initial cylindrical piece of glass tubing is upset and takes the shape shown in- Fig. 3 wherein it is formed with an intermediate enlarged wall portion providing a double-walled sealing flange 23 (Fig. 5). Then this flanged tube may be placed in a gripper 22 shown in Fig. 4 whilst in the hollow interior of this tube are provided an exhaust tube 23 and supply wires 24 and 25. With the aid of a device suitable for this purpose the upper end 26 of the glass stem tube is formed into the pinch 21 of Fig. 5, which pinch includes the supply wires 24 and and the exhaust tube 23. Owing to the fact that the stem to be formed and the projection 20a form a unit and that the projection 200. may be given any desired length, it is possible to produce a very short stem. Thus, in the stem according to Fig.

- 5 the distance d between the sealing flange 28 and the end 29 of the pinch which is remote from the said sealing flange amounts to 2 cms. It is readily possible, however, to make the stem of .much shorter length and to give dimension d a value of, for example. 5 mms.

Fig. 6 shows a method of manufacturin the glass stem tube represented in Fig. 3 which differs from that shown in Fig. 2. According to Fig. 6, the starting point is formed by two pieces of glass tubing 30 and 3| provided with flanges 32 and 33, such flanged tubes being commonly known in the art as flares. By sealin these flanges 32, 33 together at their outermost edges the form of glass stem tube shown in Fig. 3 is also obtained.

Fig. 7 represents the end of a discharge tube wherein owing to the fact that the two flanges 34 and 35, which form together the sealin flange 36 of the stem 31 in the bulb 38, are bent down, the distance 1 between the end of the base 39 and the end of the bulb surface 38 is considerably smaller than the corresponding dimension e in Fig. 1.

Ayariant of the manner of attachment of the base to the tubular projections i4 according to Fig. 8 is shown in Fig. 9 wherein the bottom 40 of a base 4i has secured in it two spring fingers 42 and 43 which extend from the inner side of the base and are provided at their ends with hooks 44 and 45. Owing to the fact that the spring fingers 4-2 and 43 are somewhat resilient, it is possible to secure such a base to the tubular projection 46 on the envelope by contractin or moving the springfingers 42, 43 towards one another and by introducing them into the aperture of the tubular projection 46. When the base 4| is slid the full distance onto the tubular projection 46, the spring fingers 42, 43 spread out, as soon as their hooked inner ends 44, 45 reach the widened portion 41 of the projection 46, and cling to the inside of the sealing flange 48, thus firmly holding the bottom 40 of the base in abutting engagement with the outer rim end of the tubular projection 46. In this form of construction the supply wires are secured to the external current supply contacts of the base in a manner similar to that described with reference to Fig. 8. In the manner shown in Fig. 9 we also obtain a very strong attachment of the bases to th lamp or tube vessel, in which event, for example, a recess in the wall of the base and a matching lug on the wall of the tubular projection 46 make impossible any rotation of the base with respect to the projection.

A further advantage of the construction according to the invention is that it is possible to obtain in a simple manner a lamp or tube wherein the current supply contacts are protected against coming into contact therewith.

Although in the description of the figures only examples of the invention in the form of an incandescent lamp and a luminous discharge tube' are given, it is evident that these constructions,

applied, for example, to radio-receiving and transmitting tubes, also fall within the scope of the invention,

What I claim is:

1. An electric device comprising an envelope having a re-entrant stem sealed within an opening therein to close the latter, said stem comprising a glass stem tube provided intermediate its ends with a laterally extending flange sealed at its periphery to the rim portions of the said envelope opening, th portion of the stem tube projecting outwardly from the envelope and having an accurately shaped outer rim end defining a base seating shoulder located in predetermined relation to the envelope, and a base fastened exclusively on the said tubular projection with a seating surface on said base in abutting engagement with the said rim end to thereby accurately position the base in predetermined relation to the envelope.

2. A tubular electric device comprising a tubular envelope having re-entrant stems sealed within openings at the opposite ends of the envelope to close the said envelope ends, said stems each comprising a glass stem tube provided intermediate its ends with a laterally extending flange sealed at its periphery to the rim portions of the respective envelope end opening, the portions of the stern tubes projecting outwardly from the opposite envelope ends having accurately shaped outer rim ends defining base seating shoulders located a predetermined distance apart, and bases fastened respectively and exclusively on the said outwardly projecting portions of the stem tubes with seating surfaces on the said bases in abutting engagement with the said rim ends to thereby accurately position the bases a Predetermined distance apart.

3. An electric device comprising an envelope having a re-entrant stem sealed within an opening therein to close the latter, said stem comprising a glass stem tube havin an intermediate enlarged wall portion providing a double-walled sealing flange sealed at its periphery to the rim portions of the said envelope opening, the portion of the stem tube projecting outwardly from the envelope having an accurately shaped outer rim end defining a base seating shoulder located in predetermined relation to the envelope, and a base mounted exclusively on the said outwardly projecting portion of the stem tube and provided with a. plurality of contractible sprin fingers extending from the inner-side of the base and insertable within the stem tube upon contraction of the fingers, said fingers havin hooked inner ends engageable with the said sealing flange to hold the base firmly in place on the outwardly projecting portion of the stem tube with a seating surface on the base in abutting engagement with said rim end to thereby accurately position the base in predetermined relation to the envelope.

4. The method of manufacturin to determined dimensions an electric device comprising an envelope having a stem sealed into an opening therein and a base mounted thereon which method comprises, forming a stem comprising a glass tube having an intermediate enlarged wall portion providing a sealing flange, fusing the periphery of the stem sealin flange to the rim portion of the said envelope opening to thereby seal the stem into the envelope, cutting off to a predetermined length the portion of the stem tube projecting outwardly from the envelope to provide an accurately shaped outer rim end defining a base seating shoulder, and fastenin a base exclusively on the said outwardly projecting portion of the stem tube with a seatin surface on the base in abutting engagement with the outer rim end of the said stein tube portion to ac- 'curately position the base in predetermined relation in the envelope.

5. The method of manufacturing to predetermined overall length an elongated electric device comprising a tubular envelope having re-entrant stems sealed into openings in its opposite ends and bases mounted on its said opposite ends which method comprises, forming a pair of stems from glass stem tubes having intermediate enlarged wall portions providing sealing flanges, fusing the peripheries of the stem sealing flanges to the rim portions of the respective envelope end openings to thereby seal the stems into the envelope, cutting off the outwardly projecting stem tube portion of at least one of said stems to provide an accurately shaped outer rim end defining a base seating shoulder and to fix a predetermined distance between the outer rim ends of the opposite stem tubes. and fastening bases exclusively on the outwardly projecting portions of the respective stem tubes with seating surfaces on said bases in abuttin engagement with the said outer rim ends of the said stem tube portions to thereby accurately position the bases a prede-' termined distance apart. 6. An electric lamp comprising an envelope having an end wall closing off an end of the en-; velope and a tubular projection extending out-g wardly beyond said end wall. a light source; mounted in said envelope and located at a defi-i nite predetermined distance from the outer rim end of said projection, and a base member mounted exclusively on said projection in abutting engagement with the said outer rim end thereof whereby to be accurately positioned relative to said filament. 7. The method of manufacturing an electrici lamp which comprises sealing end wall closure members to the opposite ends of an elongated envelope to close off the said envelope ends and proi vide tubular extensions thereon projecting out-i wardly beyond the said end walls, and cutting off a portion of at least one of said extensions to fix 4 a predetermined overall distance between the; outer rim ends of said extensions.

8. The method of manufacturing an electric lamp which comprises sealing end wall closure members to the opposite ends of an elongated envelope to close off the said envelope ends and provide tubular extensions thereon projecting outwardly beyond the said end walls, cutting off a portion of at least one of said extensions to fix a predetermined overall distance between the outer rim ends of said extensions, and securing bases exclusively to said extensions in predetermined position relative to the said outer rim ends thereof.

9. The method of manufacturing an electric lamp which comprises sealing end wall closure members to the opposite ends of an elongated en- 1 velope to close off the said envelope ends and I provide tubular extensions thereon projecting outwardly beyond the said end walls, cutting off a portion of at least one of said extensions to fix a predetermined overall distance between the outer rim ends of said extensions, and securing bases exclusively to said extensions in abutting engagement with the said outer rim ends thereof.

HENRICUS GOOSKENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED 'STATES PATENTS 

